1. Field of the Invention
The present invention relates to an upper support used in a suspension system of a motor vehicle which is constructed for easy assembling with improved efficiency, and to a method of manufacturing the upper support.
2. Discussion of the Prior Art
In a conventional suspension system of a motor vehicle, a generally cylindrical upper support is interposed between the body of the vehicle, and a piston rod of a shock absorber which is linked with an axle or arm for supporting vehicle wheels. Such an upper support is adapted to prevent input vibrations received from the wheels through the shock absorber, from being transmitted to the vehicle body, for example. The upper support usually includes a cylindrical inner rigid member to which the piston rod of the shock absorber is fixed, a cylindrical outer rigid member which is disposed radially outwardly of the inner rigid member and fixed to the vehicle body, and an elastic body interposed between the inner and outer rigid members for elastically connecting the two members.
To meet a recently increasing requirement for high-grade cars having improved vibration-isolating capability, there has been proposed a fluid-filled cylindrical upper support which contains a non-compressible fluid. The assignee of the present application has proposed such a fluid-filled upper support as disclosed in laid-open Publication No. 2-114506 of unexamined Japanese Utility Model application. The upper support disclosed therein has an annular fluid chamber filled with a non-compressible fluid, which extends between the inner and outer rigid members, in the circumferential direction of the upper support. The upper support further includes an annular resonance member which is accommodated in the fluid chamber to substantially divide the chamber into two sections, and a fluid passage through which the fluid flows between the two sections upon application of a vibrational load between the inner and outer rigid members. The thus constructed upper support exhibits a sufficiently high vibration-isolating capability, based on resonance of the fluid flowing through the passage.
In the upper support of the above type, the inner and outer rigid members and the elastic body are usually prepared independently under the atmosphere and then assembled in a mass of the non-compressible fluid for filling the fluid chamber, as disclosed in the above-indicated publication. Thus, the filling of the fluid chamber with the fluid is accomplished by assembling the inner and outer rigid members and the elastic body within the fluid means.
The outer rigid member usually has an integrally formed mounting bracket in the form of an outward flange extending radially outwardly of the outer circumferential surface thereof, and its outer dimensions are inevitably increased. Therefore, it is cumbersome to handle the outer rigid member within the fluid mass, and the assembling of the conventional upper support including the outer rigid member is a difficult job for the worker.
The upper support is usually assembled such that the inner rigid member is connected with the piston rod of the shock absorber and the outer rigid member is fixed to the vehicle body. Therefore, these rigid members must be manually positioned for a predetermined circumferential or angular relationship for connection to the shock absorber and vehicle body, and this manual positioning within the fluid mass is cumbersome Thus, the assembling of the conventional upper support cannot be automated.